Semiconductor elements (hereinafter also simply referred to as “elements”) configured with various semiconductor materials such as ICs prepared using silicon semiconductors and organic EL elements prepared using organic semiconductors are usually produced by repeatedly forming a matrix of multiple elements on a wafer substrate, then dicing the substrate into individual semiconductor chips (also referred to as bare chips).
In the explanation below, a wafer substrate having multiple semiconductor elements formed thereon (pre-dicing state) is referred to as “a semiconductor wafer”, and a semiconductor chip is sometimes simply referred to as a “chip”.
In recent years, there has been the trend toward increased use of methods of connecting (mounting) a chip to (on) an external wiring circuit substrate while the conductor portion of the wiring circuit substrate corresponds to the electrode position of the chip (e.g., flip chip bonding). An external wiring circuit substrate includes a circuit substrate for a package to be sealed together with a chip, an ordinary circuit substrate to have many other elements mounted thereon and the like.
In connecting a chip and a circuit substrate for packages, a flexible wiring circuit substrate with a contact point, known as an interposer, is sometimes interposed therebetween (JP-A-2000-349198, JP-A-2001-44589).
The above-described flexible wiring circuit substrate such as interposer is difficult to handle in manufacturing steps such as chip mounting because of their flexibility.
Therefore, it is a conventional practice to first form a flexible wiring circuit substrate on a metal support substrate to ensure adequate rigidity and improved handleability during processing, then mount a chip on the wiring circuit substrate and cover and seal the chip with a resin, and subsequently remove the metal support substrate, as disclosed in JP-A-2000-349198, JP-A-2001-44589, US Patent Publication U.S. Pat. No. 7,202,107 B2 and the like.
A chip mounted on a wiring circuit substrate and sealed with a resin, and after removal of the metal support substrate, serves as an independent semiconductor device that is equipped with a conductor for connection that facilitates connection to an external conductor (external circuit and the like) and mounting, compared with a bare chip merely having an exposed electrode pad, and that is packaged with a resin.
Usually, a large number of wiring circuit substrates for individual chips collectively form one sheet having a large area so that a large number of (e.g., about 40 to 100) chips can be mounted on the wiring circuit substrates.
Therefore, in sealing chips with a resin, a liquid resin 300 is added drop by drop to a large number of chips 200 mounted on a wiring circuit substrate 100 having a large area, as shown in FIG. 6(a), and the chips are pressed and heated using a molding die (comprising an upper die 400 and a lower die 410) to set the resin and complete the sealing, as shown in FIG. 6(b). The wiring circuit substrate 100 with a large area, which has the large number of chips integrally sealed with the resin thereon, is then has the metal support layer 110 removed therefrom, and is divided into individual semiconductor devices.
The present inventors investigated the steps of mounting a chip on a conventional flexible wiring circuit substrate as described above, of sealing the chip with a resin, and of removing the metal support layer, and found that these steps involve two complicated processes.
One of the two processes is a sealing process for setting a liquid resin in a molding die, as shown in FIGS. 6(a) and (b). The liquid form of the resin used complicates its supply and the management of its amount and quality in the sealing; fluctuations of these factors are likely to cause molding quality variation. Other problems include laborious in the maintenance of the resin supply system.
In the sealing process with a liquid resin, the liquid resin added drop by drop flows laterally while being pressed and distributed up and down in the die, so that a major lateral force sometimes works on the elements, which in turn can pose the problem of a positional shift of the elements resulting in breakage of the connection between each element and the wiring circuit substrate.
The other of the two complicated processes is the removal of the metal support substrate after resin sealing, wherein etching is unavoidably used to remove the metal support substrate because the metal support substrate and the wiring circuit substrate are formed as a unified laminated structure. Traditionally, this removal of the metal support substrate by etching has been deemed unproblematic as it is a usual process. However, the process involves complicated steps, including resist provision, immersion in etching liquid, resist removal, cleaning and the like, resulting in increased manufacturing costs. The inability to reuse the metal support substrate is also problematic because the metal support substrate disappears.
It is an object of the present invention to solve the above-described problems and simplify the entire manufacturing process, from mounting a chip on a flexible wiring circuit substrate to sealing the chip with a resin and obtain a semiconductor device.